Current-limiting reactor



June 23, 1931.

R. B. GEORGE ET AL 1,811,466

CURRENT LIMITING REACTOR Filed Sept.- 18. 1929 2 Sheets-Sheet l BY Y i 2 ATTRNEY June 23, 1931. R. B. GEORGE ET AL CURRENT LIMITING REACTOR Filed sept. 18. 1929 z'sneets-sneet 2 INVENTORS fF/Z ATTORNEY shunting thelines of magnetic force away Patented June 23, 1931 ,UNiTED STATES ROBERT B. GEORGE'AND HOINLEB B; WEST,

PATENT OFFICE OF SHARON, PENNSYLVANIA, ASSIGNORS T0 PENNSYLVANIA Application Vtiled September Our invention relates to current-limiting reactors of the oil-immersed type and "particularly to means for shielding the containifpg vessel from the stray or leakage magnetic ux. Y

If the containing vessel for the oil and the reactorcoil consistsk of ordinary steel, the hysteresis and eddycurrent and` other stray losses in the vessel become very large, due to the leakage magnetic ux, thus causing excessive heating and` objectionable losses therein.

A tank of non-magnetic `or non-metallic construction is not practicable for use as an oil container and it does not satisfactorily dissipate the heat generated within the tank. Metals of high ity are available but they must` be cast and, therefore, are not suitable for the fabrica tion oflarge oil-tight tanks', or they are composed of expensive alloys that are prohibited byeconomical conditions.

We have overcome difficulties in connection with the ordinary transformer tanks of` steel construction by providingv a path of high permeability for from thewalls of the tank. Y

A highly eicient method of shielding the casing from the leakage flux is to provide a path of low magnetic Areluctancein a part of the region between the casing and the reactor coil. This provides a suitable path of Ahigh permeability for the leakageflux.

One method of shieldingthe casingof an oil-immersed reactor consists in afxing av laminated iron shield to the inside of the reactor casing.'` This construction requires a supporting structure attached to the vcasing and a great quantity of 'iron because the shields are not as effective near the walls of the casing as they are when coil. Oneobject of our invention is to provide means for shielding the enclosing casing of an oil-immersed reactor from Vthe effects of the leakage magnetic flux that shall be simple and eicient and economical of materials. n

Another object of our invention is to proplaced nearer the j reference is made to resistivityand'low permeabilthe above-mentioned GUBEENTLIMITING nEAcfroR 18, 1929. Serial No. 393,564.

vide a magnetic shield for an oil-immersedreactor casing that shall not require an extra supporting structure. y

Another object of our invention is to provide amagnetic shield for the enclosing casing of an oil-inunersed reactor that shall Lbe integral with the reactor coil itself. j To achieve the objects of our invention, we proposeto aix a plurality of groups of iron sheets. to the outside of the reactor coil and make them integral therewith.

Our invention may be better understood if the accompanying drawings in connection with the following de-V scription. j

Figure 1is a vertical sectional view of a currenhlimiting reactor employing one embodiment of our invention;

Fig. 2 is a sectional plan view, taken on the line II-II of Fig. 1, showing the method of arranging the groups of iron sheets around the reactor; y y j Fig. 3 is a perspective View of the reactor and its magnetic shield resting on asupporting structure.

Referring to the drawings7 a current-limiting reactor Qrest's on a supporting structure 3 and's immersed in an insulating fluid 4 contained ina casing 5. The casing 5 has a cover 6 through which extend insulating bushings 7 for conducting leads 8. Y i The 'current-limiting reactor 2 comprises a cylindrical shaped'member 9 having an air core-and a winding 11 comprises a plurality of convolutions of insulated electrical conductor 12 surrounding the member 9. Vertically extending spacing members 13 are disposed between adjacent convolutions of the winding to ensure sufficient space for the circulation of oil through thewinding. The vertical members 13 are arranged in groups and each group is disposed radially ofthe center of the' reactor. Layers of paper or other insulating material 14 are wrapped aroundy the outside of the winding andare separated therefrom by the verticalfspacing members 13 to allow the circulation of oil therebetween. Y A i A magnetic shield 15 is placed around the winding 11 next to the insulating material 14. The magnetic shield 15 comprises a plurality of groups of iron sheets 16 parallel to the axis of the reactor and supported, at their ends, by annular members 17 that extend around the top and the bottom of the reactor 2. Vertical spacing members 18, of wood or similar material, are located between the groups 1G of iron sheets and are also lsupported by the annular members 17. The groups 16 of iron sheets, the spacers 1S and the annular members 17 are banded together with tape or other suitable binding material 19. If desired, the members 18 may be omitted.

The winding 11 of the reactor 2 has associated tlierewith a lower end member 2l and an upper end member that support the annular members 17 and holdthem in proper spaced relation. The end members are separated from the turns of the winding by spacing members 23 and have openings therein through which the cylindrical member 9 extends. The reactor' and its shield and end members may be variiishef'l or impregnated as a unit and placed in a tank of suitable size.

The current-limiting reactor 2 is supported by a framework 3 which comprises vertically extending .frame members 25 having members 2G welded thereto to connect them together at the top. The bottom end member 21 of the reactor rests on members 27 disposed near the bottom of the framework 3 and secured thereto by the bolts 28. The upper end member 22 is tightly held in place by members 29 and angles 31 that are secured to the frame members 25.

The groups 16 of iron sheets provide paths of high permeability for the return of the reactor flux. Preferably a high-grade iron, such as is employed for transformer cores, is utilized to keep the flux density low, so that he loss is relatively small.

It will be apparent that the shield may take different forms and be attached to the reactor winding in a dill'erent manner without departing from the spirit of our invention. It will be evident that, in applying our invention, standard transformer tanks may he employed without alteration, and no extra` framework or supporting structure is required. The shield is placed in a much more ell'ective location, thereby using less iron and 'el'lecting economies heretofore unobtainable.

lt will be apparent that we have provided a magnetic shield for oil-immersed reactors that is simple in construction and cl'licicnt and economical of materials.

Since many modifications within the spirit and scope of our invention will occur to those skilled in the art, we do not wish to be limite-d otherwise than as set forth in the appended claims.

Ve claim as our invention:

1. In a current-limiting reactor, means for along the conducting the stray magnetic flux periphery of said reactor coil when energized, said means comprising parallel groups ot continuous iron laminations attached to the periphery of aid reactor and formed integral therewith.

2. In a current-limiting reactor, a winding comprising a plurality of layers of insulated electric conductor, a plurality of groups of continuous laminations surrounding the Winding and attached 'thereto and adapted to conduct magnetic flux in a plurality of paths close to the winding when said winding is energized.

ln a current-limiting reactor, al winding comprising a plurality of convolutions of an insulated electric connuctor, a plurality of continuous laminated means disposed around the outer convolutions of the winding and made integral therewith for confining the magnetic flux to a predetermined path when the winding' is energized.

et. ln a reactor structure, a casing containing insula ing fluid, a reactor coil comprising a winding formed of an insulated electric conductor and immersed in said fluid, means for preventing the stray magnetic flux from entering said casing when said reactor is encrgized, comprising a magnetic shield oir-posed around the reactor coil and attached thereto and adapted to intercept said stray llux and to conline it to an area bounded by said shield.

5. In an oil-innnersed current-limiting reactor, a casing containing insulating fluid, a reactor coil comprising a plurality 0l" layers of insulated electric conductor immersed in said fluid, a magnetic shield for preventing the production of eddy currents in said casing when the reactor is energized, said shield comprising a plurality of spaced groups of continuous iron laminations constituting a plurality of magnetic paths circumferentially disposed about the winding parallel to the axis thereof.

G. In an oil-immersed cin'rent-limiting reactor, a casing containing insulating oil, a reactor coil comprising a plurality of layers of insulated electric conductor submerged in said oil, a magnetic shield affixed to the reactor coil at the periphery thereof for preventing' the stray flux from entering the casing, said shield con'iprising a plurality of `groups of continuous iron laminations located about said periphery to form a plurality olf low reluctance paths parallel to the axis of the coil.

In testimony whereof, we have hereunto subscribed our naines this 12th day of September, 1929.

ROBERT B. GEORGE. HOMER B. VEST. 

